How do I create these seemingly missing building block shapes in 7 Days to Die?

I have a problem with searching for some shapes used in 7DTD map buildings. Yes, I know the shape menu but I can’t find the required shapes. For example, how can I (is it even possible?) create a block which is missing in the top left position on the image below?

The same question but another building block. Is it possible to make the right rim side half size?